1. Field of the Invention
This invention relates to dry etching devices.
2. Description of the Prior Art
Generally, when a reactant gas is introduced into a reduced pressure chamber and a high frequency electric field is applied to this, the reactant gas enters the plasma state and chemically active atoms or molecules are produced, these chemically active atoms or molecules functioning as an etchant, and so enabling an etching workpiece such as a semiconductor substrate to be etched.
In this kind of device, ordinarily the plasma production region and the etching workpiece positioning region are separated by a perforated or slotted first electrode having permeability to the atoms or molecules, and the chemically active atoms or molecules produced in the plasma production region reach the etching workpiece by passing through this first electrode, but if metal is exposed in this path of movement, they attach to the metallic surface and sputter the metallic surface, reducing the density of chemically active atoms or molecules, or discharge contaminants, leading to a reduction in etching speed.
Obviously, it is desirable to limit or prevent any such reduction in etchant density and hence etching speed, and to this end it might be proposed to coat those portions, particularly the metallic portions, in the path of etchant movement with a material, such as a resin, which would protect those portions from adherence and sputtering by the chemically active atoms or molecules. However, the present inventors have also considered that is desirable that the etchant density be increased, whereby the etching speed, too, might be increased beyond that which might be expected even if no interference or contamination were to occur.